John,
What evidence is there that the Belgae and the Picts were
originally non-IE? This seems to go way too far. First of all, Pictish is almost
non-existant in any record - but what remains we do have show it to be nothing
more than a P-Celtic dialect closely related to Welsh which was Gaelicized after
the Irish inroads into Scotland. Most of the more fantastical claims to Pictish
linguistic origins seem to rest on misreadings of Ogam stones. The Pictish
inscriptions seem to use a different orthography than traditional Irish Ogam, as
might be expected by P-Celts adopting the alphabet to their own language. In any
case, the tribes of the Pictish area seem fully Celtic in form and
etymology.
Belgic seems likewise to be fully Celtic - I havn't noticed
any grand divergeneces or substrate survivals which might indicate a non-Celtic
origin to the language.
There don't seem to be any survivals of pre-Celtic languages
in Ireland whatsoever. The use of Alba for Scotland is simply a Gaelicization of
Albion - which is Elfydd in Modern Welsh - and means "visible
world."